gallium: Unify reference counting.

The core reference counting code is centralized in p_refcnt.h.

This has some consequences related to struct pipe_buffer:

* The screen member of struct pipe_buffer must be initialized, or
  pipe_buffer_reference() will crash trying to destroy a buffer with reference
  count 0. u_simple_screen takes care of this, but I may have missed some of
  the drivers not using it.
* Except for rare exceptions deep in winsys code, buffers must always be
  allocated via pipe_buffer_create() or via screen->*buffer_create() rather
  than via winsys->*buffer_create().

1 files changed, 2 insertions, 3 deletions

diff --git a/src/mesa/state_tracker/st_cb_bufferobjects.c b/src/mesa/state_tracker/st_cb_bufferobjects.c
index 28e387c399..52099232ad 100644
--- a/src/mesa/state_tracker/st_cb_bufferobjects.c
+++ b/src/mesa/state_tracker/st_cb_bufferobjects.c
@@ -74,11 +74,10 @@ st_bufferobj_alloc(GLcontext *ctx, GLuint name, GLenum target)
 static void
 st_bufferobj_free(GLcontext *ctx, struct gl_buffer_object *obj)
 {
-   struct pipe_context *pipe = st_context(ctx)->pipe;
    struct st_buffer_object *st_obj = st_buffer_object(obj);
 
    if (st_obj->buffer) 
-      pipe_buffer_reference(pipe->screen, &st_obj->buffer, NULL);
+      pipe_buffer_reference(&st_obj->buffer, NULL);
 
    _mesa_free(st_obj);
 }
@@ -165,7 +164,7 @@ st_bufferobj_data(GLcontext *ctx,
       buffer_usage = 0;
    }
 
-   pipe_buffer_reference( pipe->screen, &st_obj->buffer, NULL );
+   pipe_buffer_reference( &st_obj->buffer, NULL );
 
    st_obj->buffer = pipe_buffer_create( pipe->screen, 32, buffer_usage, size );